Direct Numerical Simulation of Surfactant-Stabilized Emulsions Morphology and Shear Viscosity in Starting Shear Flow

Journal Article · Sun Jul 01 00:00:00 EDT 2012 · Rheologica Acta

DOI:https://doi.org/10.1007/s00397-012-0628-8· OSTI ID:1049384

Skartlien, Roar; Sollum, Espen; Akselsen, Andreas; Meakin, Paul

A 3D lattice Boltzmann model for two-phase flow with amphiphilic surfactant was used to investigate the evolution of emulsion morphology and shear stress in starting shear flow. The interfacial contributions were analyzed for low and high volume fractions and varying surfactant activity. A transient viscoelastic contribution to the emulsion rheology under constant strain rate conditions was attributed to the interfacial stress. For droplet volume fractions below 0.3 and an average capillary number of about 0.25, highly elliptical droplets formed. Consistent with affine deformation models, gradual elongation of the droplets increased the shear stress at early times and reduced it at later times. Lower interfacial tension with increased surfactant activity counterbalanced the effect of increased interfacial area, and the net shear stress did not change significantly. For higher volume fractions, co-continuous phases with a complex topology were formed. The surfactant decreased the interfacial shear stress due mainly to advection of surfactant to higher curvature areas. Our results are in qualitative agreement with experimental data for polymer blends in terms of transient interfacial stresses and limited enhancement of the emulsion viscosity at larger volume fractions where the phases are co-continuous.

• Research Organization: Idaho National Lab. (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: DE-AC07-05ID14517
• OSTI ID: 1049384
• Report Number(s): INL/JOU-12-27001; RHEAAK; TRN: US201218%%1449
• Journal Information: Rheologica Acta, Vol. 51, Issue 7; ISSN 0035-4511
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
ADVECTION
BOLTZMANN EQUATION
DEFORMATION
DROPLETS
ELONGATION
EMULSIONS
LATTICE PARAMETERS
MORPHOLOGY
POLYMERS
RHEOLOGY
SHEAR
SIMULATION
STRAIN RATE
STRESSES
SURFACTANTS
THREE-DIMENSIONAL CALCULATIONS
TOPOLOGY
TRANSIENTS
TWO-PHASE FLOW
VISCOSITY
VOLUME
computer modeling
emulsion
flow visualization
morphology
shear viscosity
surfactant